Which countries have the lowest highest currency power?

Answer 1

The question is meaningless as asked. Currency value can be measured relative to domestically available goods and services (in which case the most "powerful" currency will be the one experiencing deflation; its purchasing power would increase over time) or relative to other currencies. You can also combine the two approaches to find the "real" (i.e., adjusted by purchasing power parity) exchange rates. Needless to say, the lists of "strong" and "weak" currencies you come up with would depend on how you measure the strength/weakness...

Answer 2

Highest: USD-USA; Euro-France, Germany, Spain; SL-UK
Lowest: Coins of African Countries